Set Render Transform-ing Background Blur makes it opaque. What's wrong?

I’m trying to make a background blur widget that scales to viewport size accordingly for different sized screen. This means scaling the widget without maintaining the default aspect ratio. The only way I’ve figured out how to do this is to use a Set Render Transform in the widget graph to scale the background blur widget to the viewport size.

however, it seems using render transform causes the background blur to go fully opaque. I’m not sure if this is because of super strong blur or just turning it fully opaque in color, but does anyone know what the cause of this? Or even a solution to it.